I haven't done it myself but am also interested in the responses.
I think everything you list on eBay.com shows up on any of the other int'l sites as long as you ship to those countries -- but they probably don't show in the same results (unless maybe the local results are few?). I think users sometimes have to click an extra link to get the int'l results.
So I guess an advantage of listing directly on one of the other sites is that it would show up in the main search results? Which could be good if you're selling something that might specifically interest Australians or Germans or whatever.